1. Field of the Invention
The embodiments of this invention are related to electromagnetic propulsion devices such as rail guns. In rail guns magnetic fields perpendicular to electrical current paths through an armature interacts with the path current creating forces on the armature which are perpendicular to both the current paths and magnetic field. The armature of a rail gun is located between and has moving electrical continuity with the gun's parallel power rails. The armature current flow in a rail gun is resultant a voltage potential between the power rails.
2. Description of Related Art
Devices of this application are improvements to an invention embodiment included in the applicant's patent application: Ser. No. 10/707,607. In said application's embodiment, an armature for the topic embodiment is electromagnetically propelled from breach to muzzle in the barrel cavity by the interaction of the armature's propulsion bus current with the magnetic fields of the currents in barrel wall conductors located immediately forward and aft said bus during armature barrel cavity traverse.
The propulsion bus of armatures for said embodiment is oriented orthogonal to the armature axis and, when in the barrel cavity, to armature direction of barrel cavity traverse and the barrel cavity axis. Said propulsion bus extends around most of the armature's perimeter at its surface proximal the barrel cavity wall surface. An armature for the device also includes a forward current shunt and an aft current shunt in its surface proximal the barrel cavity surface. With an armature in the barrel cavity, the armature forward current shunt is located on the muzzle side of the propulsion bus and is electrically insulated from direct electrical continuity with the rest of the armature and the aft current shunt is located on the breach side of the propulsion bus and is also insulated from direct electrical continuity with the rest of the armature except when the propulsion bus-aft shunt circuit means of the device is a current bus in the armature connecting the aft current shunt with the proximal end of the armature propulsion bus.
The embodiment includes a wall conductor assembly in the barrel cavity wall. The wall conductor assembly is comprised of the multitude of parallel, equal length barrel wall conductors; i.e. wall conductors. The wall conductors are oriented orthogonal the barrel cavity axis and located at or very close to the barrel cavity surface. Said assembly extends the length of the barrel cavity in which the device is extant and includes a barrel bus in the barrel cavity wall. The barrel bus extends parallel the cavity axis its length or has a constant rate of angular displacement at a constant radius about the cavity axis per unite barrel cavity length when the barrel cavity walls have a twist to impart spin to armatures traversing the barrel cavity. Each wall conductor has a contact means at the barrel cavity at one end and electrical continuity with the barrel bus on the other end; i.e. the wall assembly barrel bus has physical and electrical continuity with each wall conductor at the wall conductor's end opposite its contact means at the barrel cavity. The barrel bus is otherwise electrically insulated from the rest of the device.
During an armature's traverse of the barrel cavity, wall conductors that are forward the armature's propulsion bus and which have electrical continuity with the armature's forward current shunt are the forward wall conductor. Said electrical continuity is extant during the forward shunts traverse past the cavity locations of said wall conductors barrel cavity contact means. Wall conductors that are aft the armature propulsion bus and which have electrical continuity with the armature's aft current shunt are aft wall conductor. Said electrical continuity is extant during the aft shunt's traverse past the cavity locations of said wall conductor barrel cavity contact means. The barrel bus maintains electrical continuity between the instant forward and aft wall conductor during an armature's traverse of the barrel cavity.
The topic device also has two barrel power rails connected to the terminals of an outside power supply. During an armature's traverse of the barrel cavity one of the power rails has continuous sliding electrical continuity with the armature's forward current shunt. The second barrel power rail, during an armature's traverse of the barrel cavity, has continuous sliding electrical continuity with the armature propulsion bus at its end opposite the aft shunt-propulsion bus circuit means.
With an armature in the barrel cavity, a series circuit comprised of the barrel power rail that has sliding continuity with the armature forward current shunt, the armature forward current shunt, the forward wall conductor, the wall conductor assembly barrel bus, the aft wall conductor, the armature aft current shunt, the propulsion bus-aft shunt circuit means -said circuit means maintains electrical continuity between the armature aft current shunt and the proximal end of the armature propulsion bus-, the propulsion bus and the second barrel power rail is extant. With power supplied to the device via connections at the breach end of the power rails, the magnetic fields of the forward and aft wall conductor currents interact with the current flow in the armature propulsion bus propelling the armature through the barrel cavity from breach to muzzle.
With the device energized and an armature in the barrel cavity, the magnetic field of a current element at the intersection of an axis plane [i.e.—a plane containing the cavity axis and the cavity axis is also in the boundary of the plane.] with a conducting wall conductor interacts with a current element at the intersection of said plane with the propulsion bus creating forces therein with cavity axis parallel muzzle directed components which propel the armature in the barrel cavity. The axis plane intersects the propulsion bus a second time when it is extant at π arc distance about the armature axis from the first intersection and the magnetic field of the topic wall conductor current element interacts with the current element in the second intersection creating forces therein with components parallel the cavity axis and breach directed. The current element at the second intersection is at a significantly greater radius and has a greater deflection angle from the topic wall conductor current element; therefore, the forces produced in the second intersection can usually be ignored. One of the advantages of this embodiment is that it permits with a vast array of symmetric and asymmetric cavity and armature profile designs.
The force in newtons on armatures for the topic device with a cylindrical cavity is given by the general simplified equation with a cross product integrand:
      Force    =      2    ⁡          [              .9        ⁢                              ∫                          β              0                                      β              1                                ⁢                                    I              pb                        ⁢                                          r                pb                            ·                                                          ⁢                              ⅆ                θ                                      ×                          (                                                μ                  o                                ⁢                                                      I                    wc                                    /                                      (                                          2                      ⁢                      π                                        )                                                              )                        ⁢                          (                              Cos                ⁢                                                                  ⁢                                  a                  /                                      d                                          wc                      ·                      pb                                                                                  )                                          ]      
Ipb is the armature propulsion bus current. Iwc is the total aft wall conductor current or the total forward wall conductor current; i.e. Ipb=Iwc. The 2 before the bracketed terms accounts for the magnetic fields interaction with the armature propulsion bus current, Ipb, of both the forward and aft wall conductor currents which create the armature propulsion force. The 0.9 in the bracketed term is an attenuation term compensating for the effect of the magnetic field of a wall conductor current element on the second propulsion bus current element, when extant, located π radians arc distance about the armature axis from the primary intersection. The propulsion bus is at the cylindrical surface of the armature and oriented orthogonal the cavity and armature axii at radius rpb. The length in meters of the armature propulsion bus current path on which the wall conductors magnetic fields act is the integral of rpb dθ through angle β1−β0, where β0 is the angular location about the armature axis of the location on the propulsion bus that has electrical continuity with the propulsion bus-aft shunt circuit means, and β1 is the angular location about the armature axis of the propulsion bus at its sliding continuity with the barrel power rail. Permeability of free space, μ0, is 4π×10−7 Henries/meter. The distance from a current element at an axis plane intersection with a wall conductor and the current element at said axis plane's intersection with armature propulsion bus is dwc-pb and said radius has deflection angle α from a cavity axis parallel line. The Cos α term is the force component directed parallel the cavity axis. Both dwc-pb and Cos α in the (Cos α)/dwc-pb term vary for each wall conductor as its contact means are traversed by the armature current shunt and a mean effective value approximation for (Cos α)/dwc-pb may best be achieved by computer iteration.